Torpedo

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A torpedo is a type of self-propelled, self-guided projectile weapon used by many spacefaring powers. They can be distinguished from missiles because torpedoes are generally launched with a system that applies external force to the projectile to accelerate it dramatically as its fired, while missiles accelerate entirely under their own power, but this is primarily a technical distinction. Many torpedo types can also be fired without a launcher, in which case they act like missiles. They can also often be dropped unpowered like bombs.

Common Torpedo Types

Photon Torpedo

A photon torpedo being fired from an Intrepid-class starship.

Photon torpedoes are the most common type of torpedo weapon encountered across the Milky Way due to the fact that their method of operation is derived from the matter/antimatter reactors that power the majority of warp capable starships in the galaxy. All photon torpedoes contain matter and antimatter held in suspension. When contact is achieved with the target, the suspension fields deactivate to allow the reactants to combine, which results in an explosion as the matter and antimatter annihilate one another and create pure energy. The sophistication of these weapons varies, as does their yield.

Starfleet has used photon torpedoes since the early 23rd Century. These cylindrical weapons are standardized across the fleet and can be fired by nearly any Starfleet vessel. Stored in magazines near their launchers, photon torpedoes are only filled with reactants as they are being loaded for firing. Starfleet's photon torpedoes are classified by their model (designated by mark), which describes its guidance system, propulsion, and casing, as well as their class, which describes the warhead's explosive yield. As of 2401, Starfleet's standard photon torpedo is the Mark XXX torpedo casing fitted with a Class-6 warhead, which has a yield of 25 isotons. Warheads up to class 10 can be produced, but quantum torpedoes or tricobalt devices are generally used in situations where high explosive yields are required, as there are diminishing returns.

Photon torpedoes are also used by the Klingons, Cardassians, and Ferengi.

Quantum Torpedo

The starship Defiant firing two quantum torpedoes during the Dominion War.

Quantum torpedoes are advanced matter/antimatter weapons that use a zero-point chamber to focus their matter/antimatter explosion to increase its yield exponentially. Like photon torpedoes, they contain two different reactants which are kept in suspension until detonation. Upon detonation, the suspension is released and the resulting explosion is channeled into a super-durable sphere to create an zero-point reaction. Compared to a photon torpedo with the same amount of reactants, the yield of a quantum torpedo will have an explosive yield that is proportionally squared. For instance, the reactants for a class-6 25 isoton photon torpedo would create a 625 isoton explosion when used in a quantum torpedo.

Starfleet first developed quantum torpedoes in the 2370s during the Dominion War, and have generally been reserved for tactically-oriented starships, given their extremely high destructive potential. They have a similar form-factor to photon torpedoes, allowing them to be fired from most launchers, but the casings themselves require advanced construction techniques and materials that cannot easily be replicated. As of 2401, Starfleet has gone through ten iterations of the quantum torpedo, and the current model in service is the Mark X quantum torpedo, which fitted standard with a class-6 warhead. At its current maximum yield, a quantum torpedo with a class ten warhead would have an explosive yield of 2,025 isotons.

Quantum torpedoes are also used by the Klingons, Dominion, and Cardassians.

Plasma Torpedo

Several Romulan D'deridex-class warbirds firing plasma torpedoes during the Dominion War.

Plasma torpedoes store massive amounts of energized gas (i.e. plasma) either in physical storage systems very similar to other standard torpedo types or suspended in an electromagnetic field. Physical plasma torpedoes have similar range and penetration to other torpedo types, while field-suspended plasma torpedoes are only effective at close range, as they begin to dissipate quickly. Plasma torpedos have significantly lower infrastructure requirements, as they are fed from a starship's electro-plasma power grid and so can be located anywhere on the ship, not relying on matter and antimatter supplies to be piped in, but they also do not have the added safety interlock inherent in photon and quantum torpedoes provided by two separate reactants that are inert until combined.

Plasma torpedoes are used primarily by the Romulans, Borg, Orions, and Nausicaans.

Uncommon Torpedo Types

Tricobalt Devices

Tricobalt devices are extremely powerful explosives, generally used for mining and demolitions purposes, as they are ineffective on shielded targets. They are not standard equipment carried on Starfleet vessels. While not considered subspace weapons per se, they are capable of creating explosions large enough to damage subspace, particularly in areas where subspace is already degraded in some way.

Gravimetric Torpedo

The starship Voyager was able to modify several photon torpedoes with gravimetric charges, which increased their yield significantly, though not at the same exponential rate that a quantum torpedo does. A starship might modify its photon torpedoes in this way if there is a specific application that requires a higher yield, but tricobalt devices or quantum torpedoes are not available.

Transphasic Torpedoes

Transphasic torpedoes couple a quantum warhead with an energy phasing system that allows a warhead to phase out of this dimension to bypass shields, armor, and a vessel's superstructure to detonate deep within it. They are extremely devastating weapons that even the Borg were unable to defend against. The only known use of this weapon in this timeline was by the starship Voyager during her return to the Alpha Quadrant. Because this equipment came from a possible future, it violates the Temporal Prime Directive and is both prohibited from use and is highly classified, like the rest of The Voyager Technology.

Torpedo Launch Systems

As mentioned in the introductions, torpedoes are primarily launched with systems that accelerate them with external forces upon firing. Most torpedo launchers operate either with the expulsion of compressed gas, electromagnetic energy, or a combination of these forces. Once launched, the torpedo's internal guidance and propulsion systems take over and make any necessary corrections to ensure they make contact with the target.

Single-Fire Launchers

The Constitution II-class Enterprise-A and the starship Excelsior both firing their single-fire launchers.

Sometimes just called a "torpedo tube," single-fire launchers are the most common type of torpedo launcher. In these systems, torpedoes are armed and loaded either directly into the launch tube or into a staging chamber. Once in the tube, compressed gas or electromagnetic forces propel the torpedo at a high rate of speed out into space. As the name suggests, they fire one torpedo at a time, but systems with staging chambers can have multiple torpedoes on hot standby to be loaded into the chamber in rapid succession. For instance, the class-4 torpedo launchers on the Constitution II were cable of launching one torpedo every two seconds, with up to four warheads held just behind the launch tube. While burst-fire launchers must be ever-wider to handle larger salvos, single-fire launchers' successive firing rate can be increased either with longer loading tracks, vertical staging systems, or wider staging chambers, which makes them more adaptable to the internal dynamics of various ships.

The original Enterprise in refit configuration firing two torpedoes in rapid succession, demonstrating the capability of single-fire launchers to hold additional rounds in immediate reserve, even though they only fire one torpedo at a time.

Starfleet single-fire launchers are designated in types based on the number of rounds they can hold for immediate firing, such as the Type-4 system mentioned above. Vessels employing single-fire rather than burst-fire torpedo launchers often have these systems mounted in pairs, which allows them to lay down a near-constant stream of fire by alternating between launchers. Type-6 launchers are standard on Starfleet vessels built after 2350. There's no theoretical limit to the number of torpedoes that could be held ready to fire, but higher type numbers require larger amounts of space, space which is filled with armed torpedoes, which means that accidental explosions can be significantly harder to contain.

Burst-Fire Launchers

A Galaxy-class starship firing a salvo of torpedoes from her forward launcher at multiple Klingon targets. Note how the torpedoes remain together as a cluster for a few seconds before splitting off.

Burst-fire launchers are torpedo launch systems that can fire multiple torpedoes simultaneously. This can be accomplished either through having multiple launch tubes collected together into a composite launcher or through using extremely large torpedo tubes which can contain more than one torpedo together in a cluster held together by an electromagnetic field, which dissipates several seconds after launch to allow the torpedoes to separate and reach their targets.

Starfleet first developed burst-fire torpedo launchers in the 2350s for deployment aboard the Galaxy-class explorer, with initial prototypes coming into service aboard the Cheyenne and Springfield. Like with single-fire launchers, they are designated based on the number of warheads they can launch at any one time, as well as the number of salvos they can hold in reserve. The launchers aboard Galaxy-class starships are Type-10, as they can fire a single salvo of 10 torpedoes, but must reload before firing again. The launchers aboard the newer Odyssey-class starships are Type-15B, meaning that they can fire salvos of 15 torpedoes and hold two salvos immediately in reserve. As with single-fire launchers, increasing launch capacity requires lots of space within a vessel. The largest launchers currently in service are the Type-20C launchers fitted to Guardian and Probert-class stations, which can launch salvos of 20, with three salvos held in reserve. It is worth noting that a vessel or station could quickly deplete its torpedo supplies using these launchers, and these numbers reflect their absolute maximum capabilities. Starfleet tactical doctrine calls for the minimal use of force required to disable a threat, meaning that most situations will call for single-fire or small salvo uses of these launchers.

Torpedo Turrets

The Sovereign-class USS Enterpise-E firing quantum torpedoes from its torpedo turret, alongside an Akira-class starship launching photon torpedoes from a single-fire launcher, at the Battle of Sector 001.

Torpedo turrets are launch systems where the firing angle of the weapon can be changed independently of the ship's heading. Typically engineered for rapid fire, they can either be burst or single fire systems. The advantage they offer is a much wider firing arc than other torpedo launchers, but their equipment is complex and bulky.

Starfleet only employs torpedo turrets on a small number of starship classes, notably the Sovereign-class exploratory cruiser and the Obena-class emissary. These launchers are capable of firing photon or quantum torpedoes at a rate of two per second, using a single-fire launcher with a vertical loading track that feeds torpedoes from the magazine above the turret into the launch chamber below. They are technically classified as Type-10 single-fire launchers, but their loading speed is so high that they can theoretically empty their entire magazine without pausing. Maintaining the systems necessary to accomplish this while also allowing the turret to track is difficult, which has limited their widespread deployment across the fleet.

Torpedoes In-Play

Starfleet Photon and Quantum Torpedo Warheads

Warhead Class	Photon Yield	Quantum Yield
1	2.5 isotons	6.25 isotons
2	5.0 isotons	25.00 isotons
3	10.0 isotons	100.00 isotons
4	15.0 isotons	225.00 isotons
5	20.0 isotons	400.00 isotons
6	25.0 isotons	625.00 isotons
7	30.0 isotons	900.00 isotons
8	35.0 isotons	1225.00 isotons
9	40.0 isotons	1600.00 isotons
10	45.0 isotons	2025.00 isotons

• Nearly all vessels can fire some form of torpedo, though the type, number, and power of these weapons varies considerably. As of the 25th century, Starfleet vessels still carry photon torpedoes, as they are easier to produce and maintain than quantum torpedoes, but in theory both weapon types could be fired from any launcher type.
• The type-6 photon torpedo was standard during Star Trek: Voyager, and represents a middle-of-the-range weapon. This is the weapon most Starfleet ships will still use, as Starfleet's philosophy is that the minimum amount of force should always be used.
• Isotons are inconsistently described in Star Trek, so the chart to the right is provided primarily for your own reference to see the relative difference between these weapon types. In the Memory Alpha article, you can see that even the same torpedo type is describe inconsistently in terms of yield, so Bravo Fleet canon takes a middle position.
  • 25 isotons is enough to wipe out a city, so the most powerful quantum torpedoes could probably blow up whole moons.
• A quantum torpedo is exponentially (literally) more powerful than the equivalent fuel in a photon torpedo, so using them represents a serious escalation.
• Not all specification articles specify precisely which launcher system is used on each ship class, as the team goes back and revises. If it's not specified, you're probably dealing with a single-fire launcher. Burst-fire launchers are very large pieces of equipment and so must be on larger vessels.